Specialized glasses such as those used as substrates in the manufacture of liquid crystal displays and similar devices have demanding standards regarding surface defects. One source of such defects is glass chips generated during the separation of panes of glass from a moving ribbon of glass.
In the past, such separation has been performed manually using the following steps. First, a separation line (score line) was formed in the ribbon of glass using an automated moving scribe/moving anvil assembly. Then, the operator attached a vacuum cup array to the glass below the score line and applied a bending moment to the glass to cause it to break at the score line and thus form the desired glass pane. This breaking produced a newly-formed leading edge on the moving ribbon and a newly-formed trailing edge on the glass pane.
To avoid damage to these newly-formed edges, the operator would endeavor to immediately move the pane away from the oncoming leading edge of the ribbon. As will be evident, this was not easy to do because, among other things, it was difficult to apply the same bending moment to the pane each time it was to be separated form the moving ribbon. Different bending moments resulted in different orientations for the pane at the time of separation, making it even more difficult to avoid edge contact. Different bending moments also affect the break signature or quality of the break independent of edge contact. Moreover, even with identical bending moments, individual panes of glass can separate at different angles making the avoidance of edge contact even more difficult to achieve.
As a result, only highly skilled and trained operators could perform the pane separation procedure, and even with such operators, edge contact and break signature variation occurred leading to rejected panes.